00:00 - It's happening, isn't it?
00:03 - Welcome to WatchMojo.
00:04 And today we're looking at the true story behind the bombs from Oppenheimer.
00:07 - I needed to be engaged with it.
00:09 I wanted it to have bigger possibilities.
00:11 I wanted to do it in a way that I was excited about.
00:16 - Just before dawn on July 16th, 1945, generals and scientists watched nervously from trenches
00:22 and bunkers for a flash in the New Mexico desert.
00:25 When it came, the blast melted sand into glass, lit up the nearby mountains, and punched a
00:30 hole through the clouds.
00:31 - Army camera six miles away recorded the historic moment in the black of night.
00:41 - Recordings capture the roar of the shockwave and towering mushroom cloud, but not the otherworldly
00:46 purple light that faded into green and then white.
00:49 The bomb's architect, physicist J. Robert Oppenheimer, would recall feeling a sense
00:53 of awe and somberness.
00:55 - Now I am become death, the destroyer of worlds.
00:59 I suppose we all thought that one way or another.
01:05 - Witnesses, however, remember him as relieved and triumphant.
01:09 The idea for the atomic bomb came from rapid developments in atomic theory in the 1930s.
01:14 The theory that matter consisted of discrete particles had been around for some time, but
01:18 it was only proven in 1911 when French physicist Jean Perrin verified an earlier theory of
01:23 Albert Einstein's.
01:25 Within decades, physicists had sketched out the atomic structure we're familiar with today,
01:29 a nucleus of protons and neutrons surrounded by a cloud of electrons.
01:34 Then came a crucial breakthrough.
01:36 In 1938, German chemists Otto Hahn and Fritz Strassmann bombarded uranium atoms with neutrons
01:41 and split them in half, releasing considerable energy.
01:44 They had stumbled on nuclear fission, a power that was about to change the world.
01:49 Once they understood what they'd achieved, Hahn and Strassmann predicted that the reaction's
01:53 release of additional neutrons could lead to a chain reaction.
01:57 The double-edged sword of this realization, which could deliver us both a new source of
02:01 energy and unprecedented destruction, was already apparent in May 1939 when French physicists
02:07 filed three patents, two for nuclear power production and the third for an atomic bomb.
02:12 It was a time of growing global tensions.
02:15 In Germany, Nazi Party leader Adolf Hitler had ridden a populist wave of national grievance
02:20 to power, encouraging Germans to see themselves as the victims of World War I and its aftermath.
02:25 He stoked resentment at the harsh terms of the Treaty of Versailles, which had required
02:29 Germany to demilitarize and pay substantial reparations, and at Jews and socialists who,
02:35 he said, had lost them the war.
02:37 Nazi anger was a dam ready to burst and wash over Europe and, potentially, the world.
02:43 In August 1939, as war loomed on the horizon, physicists Leo Szilard and Albert Einstein
02:48 wrote a letter to US President Franklin D. Roosevelt, warning that Germany might already
02:53 be developing atomic weapons.
02:55 The following month, Germany invaded Poland, igniting World War II.
02:59 And that was the context in which Roosevelt finally read the letter in October.
03:04 Alarmed, Roosevelt established an atomic committee.
03:07 But it was thought at first that a vast amount of uranium would be needed, rendering such
03:11 a bomb impractical.
03:12 In March 1940, however, physicists Otto Frisch and Rudolf Peierls figured out that a small
03:17 amount of a specific isotope, uranium-235, would be sufficient to start a nuclear chain
03:23 reaction.
03:24 In December 1941, the Japanese bombing of Pearl Harbor drew the US into the war.
03:29 And the following year, the US initiated the Manhattan Project, a secret program to build
03:34 a bomb that could win the war.
03:36 The project was headed by Major General Leslie Groves, with physicist J. Robert Oppenheimer
03:41 directing the actual design of the bombs at Los Alamos Laboratory.
03:45 The introspective intellectual had never led such a large project, but Groves sensed in
03:49 him a quote "overweening ambition" and that quote "he would let nothing interfere with
03:54 the successful accomplishment of his task and thus his place in scientific history."
03:59 Spurring the project on was a terrible fear that Germany would beat the Allies to the
04:03 bomb.
04:04 Ironically, that same year, Germany had actually abandoned their nuclear program, lacking resources.
04:10 But the Allies didn't know that.
04:11 "Of a 12-month head start, 18.
04:14 How could you possibly know that?"
04:17 Oppenheimer proved to be a capable leader.
04:19 Under his direction, the project pursued two distinct designs, based on different methods
04:23 of initiating a nuclear chain reaction.
04:26 The simple gun-type design would shoot one piece of fissile material into another.
04:30 An earlier version, Thin Man, which used plutonium, was abandoned as risking predetonation.
04:35 Its successor, Little Boy, used uranium-235 instead.
04:39 Oppenheimer used plutonium in the second design, a more complex implosion type that involved
04:44 detonating explosives around a plutonium core.
04:47 This produced the bomb, named the "Gadget," used in the Trinity Test in July 1945, and
04:52 a bomb called Fat Man.
04:54 By the time of the Trinity Test, Germany had already surrendered.
04:58 But Japan fought on.
05:00 On July 26th, the Allies called for Japan's unconditional surrender, warning of quote
05:05 "prompt and utter destruction."
05:07 Japan refused, and President Harry S. Truman authorized the use of the bombs.
05:12 "A short time ago, an American airplane dropped one bomb on Hiroshima and destroyed its usefulness
05:20 to the enemy."
05:21 It was 8.15 on August 6th when the U.S. bomber Enola Gay released Little Boy over the Japanese
05:27 city Hiroshima.
05:29 Parents and children were having breakfast at home, or on their way to work and school.
05:33 The bomb detonated 1,900 feet over the city.
05:36 The blast wave tore through buildings and people, and created a firestorm in its wake.
05:41 At least 70,000 were killed.
05:44 Some survived with horrible burns, barely recognizable.
05:47 Three days later, when Japan still refused to surrender unconditionally, the U.S. dropped
05:52 the even more powerful Fat Man on Nagasaki.
05:55 The total death toll of the bombs is estimated to be between 129,000 and 226,000 people,
06:03 mostly civilians.
06:04 As Japan admitted defeat, Americans celebrated in the street.
06:08 The war was over.
06:10 In the months afterwards, journalists would discover scenes of horror at Hiroshima and
06:14 Nagasaki, where people were vomiting blood and dying from a mysterious affliction, radiation
06:19 sickness.
06:20 The military sought to suppress reports from the ground, and the U.S. government to frame
06:24 the bombings of civilian targets as "unnecessary evil."
06:28 A guilt-wracked Oppenheimer would confront Truman, saying he felt he had blood on his
06:32 hands.
06:33 Truman angrily threw him out.
06:35 He would go on to oppose the development of the even more powerful hydrogen bomb.
06:40 Accused of disloyalty, in part due to his association with communists, he was stripped
06:44 of his security clearance, ending his role in government policy.
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07:04 Today, there remain an estimated 13,080 nuclear warheads in the world.
07:10 Ninety percent of them are owned by the U.S. and Russia, thanks to disarmament and non-proliferation
07:15 treaties.
07:16 That is considerably less than the 70,000 warheads that existed at the peak of the Cold
07:21 War, but still enough to cause massive global destruction.
07:25 Other nations with nukes include the UK, France, China, and unofficially, India, Pakistan,
07:32 North Korea, and Israel.
07:33 Since 1947, the Bulletin of Atomic Scientists' Doomsday Clock has tracked how close we seem
07:39 to be to human-made global catastrophe.
07:42 On January 24th, 2023, the clock was moved forward to 90 seconds to midnight, marking,
07:48 quote, "a time of unprecedented danger."
07:51 The images of the destruction that the bombs wrought continue to haunt us, reminding us
07:56 of the horrific power we now hold in our hands.
07:59 "Eight, seven, six."
08:08 "Five, four, three, two, one."
08:23 "Go."
08:27 (upbeat music)
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